A common type of wide agricultural implement includes right and left wing frames pivotally attached to a center frame where the wing frames fold rearward for transport. Ground engaging tools such as discs, harrows and packers are mounted on the center and wing frames.
A hitch frame is mounted on center wheels at a rear end thereof and extends forward from the center wheels to a hitch tongue adapted to be attached to the drawbar of a towing vehicle. A center frame is pivotally mounted on the rear end of the hitch frame about a hitch pivot axis that is perpendicular to the operating travel direction. Right and left elongate wing tool bars are in turn pivotally attached to outer ends of the center frame about right and left wing pivot axes that are aligned with the operating travel direction when in the operating position so that the wing frames can pivot up and down with respect to the center frame to follow ground contours. Wing operating wheels are attached to outer portions of each wing to support the wings in the operating position.
For transport the rear end of the center frame is pivoted upward about the hitch pivot axis and the rear ends of the wing frames, attached to the center section, follow the center section and pivot upward moving the ground engaging tools above the ground. Typically as the wing frames pivot upward, wing transport wheels move down into contact with the ground and the wing operating wheels are raised above the ground. The wing operating wheels are oriented to roll in the operating travel direction when the wings are in the operating position, and the wing transport wheels are oriented to roll perpendicular to the operating travel direction. Thus when the rear ends of the center and wing frames are raised to a position where the wing pivot axes is generally vertical, the operator can move the implement forward in the operating travel direction and as the center frame moves in the operating travel direction, the wing frames move to a position trailing behind the center frame and substantially aligned with the operating travel direction.
This system is commonly used in lighter implements such as harrows where the wing frames comprise simply a single laterally extending member, such as disclosed in U.S. Pat. No. 4,821,809 to Summach, et al., U.S. Pat. No. 4,418,762 to Page, U.S. Pat. No. 3,640,345 to Sosalla, and U.S. Pat. No. 3,539,016 to Bauer et al.
Heavier implements with rear folding wing frames are also known. U.S. Pat. No. 7,581,597 to Neudorf et al. discloses an air seeder implement with no center section and with rear folding wings where again the wing frames comprise simply a single laterally extending member to which the ground engaging tools are attached. U.S. Pat. No. 7,861,795 to Dillon discloses an implement where the front of the wing sections is raised prior to folding the wings rearward. U.S. Pat. No. 9,198,342 to Friggstad discloses an air seeder implement with no center section where the wing frames fold rearward for transport and forward portions of the wing frames fold up. In the operating position the wing frames are connected at both front and rear portions thereof to make a substantially rigid structure.